The field of the invention relates to biologic disks, replacements, and/or structures principally for human and animal use.
The normal human disk is made of multiple layers (13) of collagen and a highly hydrophilic mucopolysaccharide center. This is similar to a radial car tire. This construct converts compression axial loads on the gelatinous center to the outer collagen fibers as tensile forces. This tissue is highly viscoelastic. The construct provides both mobility and stability to the spinal joints. Unfortunately the chemical properties of the gelatinous center material (nucleus pulposis) deteriorate with age and become less hydrophilic. Forces are not converted from compression to tension as well and more compression and torsional loads are conferred to the outer layers (annulus). These layers deteriorate and lose their integrity forming multiple small tears, which coalesce and become large ones. The disk loses height; material bulges or extrudes into inappropriate locations through ruptured annular walls. The grip on the vertebra slackens and chronic nerve stimulation occurs due to release of degenerated debris and loss of space for the nerves. Thus we have 80% of the population with significant disabling symptoms at some time in their lives from lumbar spine disease. The only ailment more common than back pain is the common cold.
In orthopedic surgery badly deteriorated joints are either fused together to control pain or joint replacement procedures are performed to control pain without complete loss of the motion function of the joint. Obviously the maintaining of as much of the normal motion in the joint as is possible is ideal. When joints are fused, adjacent joints must work much harder in compensation, and may become symptomatic also. In the lumbar spine there are five joints and the hips that share in the motion function so there is more forgiveness when one or more, but fewer than when all, are fused together. However, very often there are several deteriorated joints. Fusing too many joint results in such overload of adjacent joint structures that as many problems are created by fusing as are solved. The treatment of hip and knee arthritis has been absolutely revolutionized by joint replacement surgery. The spine is still in the dark ages because of no viable joint replacement procedure exists.
The spinal joint is actually three joints, two facet joints and one disk. The three joints interact to allow the right balance of mobility and stability for spine function as we know it. Research has shown that deterioration occurs first in the disk, and then as a consequence of changes in the facet joints. Therefore, replacing the disk function will halt deterioration of the entire joint complex.
Much work has been done in order to develop mechanical disk replacements. None have been shown to have lasting effectiveness. Problems associated with maintaining the location, size, wear, and fatigue failure have been the stumbling blocks for prior prototypes.
A biologically compatible prosthesis will certainly be the future reality for disk replacement. Hair which is immunologically silent, strong, very modifiable and has the potential for biological incorporation is the answer. There are two components to the disk as mentioned above. These include the annulus and the nucleus pulposis. The former, in one embodiment, can be constructed similarly to a textile from autologous or homologous hair. The latter, in one embodiment, can be constructed by processing keratin sulfate or utilizing another substance such as a hydrophilic gel, poloyxymer 407, and/or regenerated in vivo by utilization of morphogenetic growth factors. Recombinant growth factors are being produced now and some do produce the same substances in the nucleus pulposis under appropriate conditions in vivo. One embodiment includes a xe2x80x9chair bagxe2x80x9d inserted into the center of the human disk through a small incision and that is then filled with a gelatinous substance containing cartilage growth factors. As the body incorporates the tissue, the new somewhat similar xe2x80x9cdiskxe2x80x9d forms within the deteriorated one. The tissue may be more fibrotic than normal, and have less elasticity than normal. This would nevertheless meet the goal of allowing motion and stability, and therefore greatly improve symptornatology.
Other aspects of the invention use hair as a biologic implant, replacement, and/or structure. Such implants can be cosmetic implants. Additional blood vessel replacements can be constructed from hair. Further, hair can be used for joint resurfacing or meniscal replacement. Still further, hair can be used as a biological endoprosthesis for ligament and tendons.